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Scientists have discovered that two of the key coral species forming Florida's reef are now ecologically extinct following a withering ocean heatwave caused catastrophic losses.

The Meaning Behind 'Functional Extinction' Signifies

The near-total decline of these corals, which once served as the foundation of reefs in Florida and the Caribbean, means they can no longer play their previously crucial role in constructing and maintaining reef ecosystems that support a variety of marine life.

Functional extinction is a phase before global extinction, a danger that now hangs for many coral species.

Scientists recently alerted that a critical threshold had been reached, meaning corals around the world are set to be wiped out due to global heating, which is raising ocean temperatures to unbearable levels.

Researcher Perspective

"We're running out of time," stated Ross Cunning of the recent research. "Severe marine heatwaves are becoming more frequent and intense due to global warming, and absent swift, decisive measures to slow ocean warming and boost coral resilience, we face the danger of the disappearance of even more corals from reefs in Florida and around the world."

The Recent Study

The recent study, published in the Science journal, examined the fate of staghorn coral and elkhorn coral corals off the Florida coast after a intense marine heatwave in 2023.

This event raised temperatures on Florida's fraying coral reefs to their highest levels in over 150 years.

The two species are intricate, reef-building corals and are identified because they resemble, respectively, the antlers of male deer and elk.

However, researchers who conducted diver surveys of over fifty-two thousand colonies of the species, across 391 sites along Florida's coast, found extensive, often catastrophic, losses.

Regional Effects

• Along the Florida Keys, death rates hit ninety-eight percent and even one hundred percent, showing a total eradication of the corals.
• In southeastern Florida, where temperatures have been lower, death rates were lower, at about thirty-eight percent.

Historical and Present Threats

The two Acropora species had already suffered from many years of regional pressures in Florida, such as contaminated water from pollutants that wash off the land, as well as disease.

But the 2023 marine heatwave has been lethal for these temperature-sensitive species.

The 2023 heat event caused the ninth episode of bleaching on the Florida reef – a phenomenon whereby corals become thermally stressed and eject the algae partners living in their tissues, causing them to become bleached white.

If temperatures stay high, the corals perish completely.

Global Consequences

Worldwide, coral reefs are among the ecosystems most vulnerable to the human-caused climate emergency.

This poses a major threat to:

• One-fourth of all ocean life that relies upon what are essentially the rainforests of the sea.
• Millions of people who depend upon corals to sustain fish that they can eat and earn a livelihood from.

Corals also serve as a protective barrier to safeguard our shorelines from intense hurricanes, which are themselves being worsened by increasing global heat.

Conservation Attempts

In a last-ditch effort to prevent a decline of endangered corals, scientists have established repositories of Acropora in marine facilities and offshore coral nurseries.

Attempts have been undertaken to reseed corals on reefs in Florida, as well, in an effort to regain some of the 90% of coral cover lost off the state in the past four decades.

But as climate change continues to intensify, there is little hope of continued existence of these species absent significant actions, scientists caution.

Further Expert Commentary

"Elkhorn corals, especially, are some of the key wave-breaking coral species in the area," said a study co-author, a ocean scientist at the University of Miami.

"They were once abundant on shallow reef tops in the Caribbean, and if we want our reefs to continue protecting our coastlines from flooding during storms, it is worthwhile taking extraordinary measures to ensure we don't lose these corals completely."